The detection box of SPOT earth observation camera

Structural and instrumental features of the SPOT satellite high resolution visible (HRV) camera, scheduled for launch in 1985, are outlined. The HRV will function at 0.5-0.6, 0.6-0.7, and 0.8-0.9 micron as well as in the panchromatic 0.5-0.75 micron bands, each fitted with 6000 CCD elements that yield a 10 m x 10 m ground image in the panchromatic and 20 m x 20 m image in the spectral bands. A beam splitter separates the incoming radiance, which is also directed through spectral filters. Four CCD elements are mounted on each optical divider to give 1728 points in a 6000 point continuous array. The elements were selected on the bases of the spatial and spectral response uniformity, contrast transmittance, responsivity, linearity, SNR, darkness voltage, and geometrical characteristics. The primary structure and support structural materials and configurations were chosen to minimize thermal absorptance and thermally-induced distortions, as well as to ensure constant thermal dissipation.